From: Mark Salter msalter@redhat.com
ACPI 5.1 adds a _CCA object to indicate memory coherency of a bus master device. It is an integer with zero meaning non-coherent and one meaning coherent. This attribute may be inherited from a parent device. It may also be missing entirely, in which case, an architecture-specific default is assumed.
This patch adds a utility function to parse a device handle (and its parents) for a _CCA object and return the coherency attribute if found.
Signed-off-by: Mark Salter msalter@redhat.com --- drivers/acpi/utils.c | 26 ++++++++++++++++++++++++++ include/acpi/acpi_bus.h | 2 ++ 2 files changed, 28 insertions(+)
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c index 371ac12..af325a7 100644 --- a/drivers/acpi/utils.c +++ b/drivers/acpi/utils.c @@ -723,3 +723,29 @@ bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs) return false; } EXPORT_SYMBOL(acpi_check_dsm); + +/** + * acpi_check_coherency - check for memory coherency of a device + * @handle: ACPI device handle + * @val: Pointer to returned value + * + * Search a device and its parents for a _CCA method and return + * its value. + */ +acpi_status acpi_check_coherency(acpi_handle handle, int *val) +{ + unsigned long long data; + acpi_status status; + + do { + status = acpi_evaluate_integer(handle, "_CCA", NULL, &data); + if (!ACPI_FAILURE(status)) { + *val = data; + break; + } + status = acpi_get_parent(handle, &handle); + } while (!ACPI_FAILURE(status)); + + return status; +} +EXPORT_SYMBOL(acpi_check_coherency); diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index a361f43..0d4ce14 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -69,6 +69,8 @@ bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs); union acpi_object *acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func, union acpi_object *argv4);
+acpi_status acpi_check_coherency(acpi_handle handle, int *val); + static inline union acpi_object * acpi_evaluate_dsm_typed(acpi_handle handle, const u8 *uuid, int rev, int func, union acpi_object *argv4, acpi_object_type type)